1. Technical Field
The present invention relates to a liquid ejecting head including a piezoelectric element that has an electrode which causes a pressure change in a pressure generation chamber that is in communication with a nozzle opening, and a piezoelectric body layer, a liquid ejecting apparatus, and a piezoelectric element.
2. Related Art
High piezoelectric characteristics are sought after in piezoelectric materials that are used as piezoelectric body layers that configure liquid ejecting heads, and it is possible to include lead zirconate titanate (PZT) as a representative example of a piezoelectric material (for example, refer to JP-A-2001-223404). However, from an environmental perspective, non-lead piezoelectric materials and piezoelectric materials with reduced lead contents are desirable. For example, BiFeO3-based piezoelectric materials that include bismuth and iron are examples of piezoelectric materials that do not contain lead. A composite oxide that is represented as mixed crystals of bismuth manganate ferrate (Bi(Fe, Mn)O3) and barium titanate (BaTiO3) is a specific example thereof (for example, refer to JP-A-2009-252789).
In addition, in order to perform high-quality printing, as a drive waveform that is used in an ink jet type recording head, it is possible to reduce the weight of ink droplets that are discharged, and to reduce a recording dot diameter by performing so-called “pull-striking”, which causes a pressure generation chamber in which ink is accommodated to contract after causing the pressure generation chamber to expand (for example, refer to JP-A-55-17589).
In an ink jet type recording head that uses deflection displacement type piezoelectric vibrations, in order to perform the aforementioned “pull-striking”, an intermediate voltage Vm is set as a base point, and a drive waveform that includes a first signal for expanding a pressure generation chamber, a second signal for contracting the pressure generation chamber in order to discharge ink, and a third signal for reverting a contracted pressure generation chamber to the original state thereof after ink discharge, is used. Therefore, during non-driving the DC voltage of the intermediate voltage Vm is in a state of being applied to a piezoelectric body.
Since the aforementioned PZT has a high insulating property, up until now, the intermediate voltage Vm was not a problem. In this manner, the reason why PZT has an insulating property that is sufficiently high for the Vm not to become a problem is that PZT is a band insulating body that has a wide band gap.
On the other hand, BiFeO3 is Mott insulating body in which a band gap is generated by interactions between electrons of the 3d orbital (on-site Coulomb interaction). Therefore, in BiFeO3-based piezoelectric materials, as disclosed in JP-A-2009-252789, a countermeasure that reduces the amount of leakage current by adding Mn, the degree of freedom of d electrons and valence of which is high, as an additive has been adopted.
However, in countermeasures to reduce the amount of leakage current, since Mn also forms an impurity level at the same time it is not possible to realize an insulating property that is common to PZT. From this kind of circumstance, in order to use a BiFeO3-based piezoelectric material as a piezoelectric material of a liquid ejecting head that is as reliable as or more reliable than PZT, in addition to improving the insulation property it is necessary to improve the resistance property to DC voltage.